It’s hard to imagine an easier way to set up communications between an Android device and an Arduino using Bluetooth ... cheap and ubiquitous HC-05 Bluetooth module. Having picked up one of ...

Fortunately for hardware hackers, such an architecture ... cut the trace leading to the Bluetooth interface module and soldered a wire so the switch now pulls an Arduino pin to ground when pressed.

The HID Relay takes the form of a small adapter that has been built using an Arduino Pro Mini, a Bluetooth module, a USB host shield together with a few other components. Check out the video below ...